| Buckwheat belongs to Fagopyrum Mill.(Polygonaceae) and it distributs in Asia and Europe extensively.In general,only two species of buckwheat,namely common buckwheat(Fagopyrum esculentum) and tartary buckwheat(Fagopyrum eseulentum) are cultivated species.Many kinds of nutritional ingredients are rich in buckwheat.Flavones, flavonoids,sterols,fagopyrin,and thiamin-binding proteins in buckwheat seeds possess potential effects in treating some chronic diseases.In buckwheat,the main component of flavonoids(80%) is rutin.Rutin can reduce high blood pressure,decrease the permeability of the blood vessels,reduce the risk of arteriosclerosis,antagonize the increase of capillary fragility associated with haemorrhagic disease,and have an antioedema effect and antioxidant activity.Genetic diversity of buckwheat germplasms were studied based on biochemistry and morphological markers The main results were described as following:1.Three segments of chloroplast DNA(cpDNA),namely matK,rbcL and trnL-F spacer were determined in 24 taxon of Fagopyrum were cloned and sequenced,some related published sequences of Fagopyrum were analyzed in this paper.Molecular phylogenetic relationships of the related taxon of Fagopyrum were studied.The result indicated that evolutionary rate of trnL-F spacer was faster than that of matK,and evolutionary rate of matK was faster than that of rbcL in Fagopyrum,the genetic diversity between the cymosurn group and the urophyllum group was larger,and within the urophyllum group was higher than that of within the cymosum group.The phylogenetic relationships were inferred using the maximum-parsimony and Bayesian analyses,and the two methods produced trees with largerly congruent topology.Better phylogenetic resolution was obtained from the matK and trnL-F dataset compared to the rbcL dataset. Except for very few materials,the cymosum group and the urophyllum group formed two monophyletic branches,respectively,matK,rbcL and trnL-F spacer sequences within the species of F.tataricum and F.tataricum ssp.potanini,F.esculentum and F.esculentum ssp. ancestralis,F.gracilipes and F.gracilipes var.odantopterum were homologous and there had close relationships within these species and their subspecies.The genetic diversity of F. cymosum and F.urophyllum was higher,and the relationships within two species were farther,relatively.F.eymosum and F.tataricum were much more closely related than that of F.cymosum and F.eseulentum.Based on matK and rbcL analysis showed that F. polychromofolium had close relationships with the cymosum group,such as F.cymosum,F. esculentum and their wild relatives,based on trnL-F analysis showed that F. polychromofolium had closed relationships with F.caudatum and F.urophyllum which belong to the urophyllum group,while had distant relationships with F.cymosum,F. esculentum and their wild relatives.2.The internal transcribed spacer(ITS) regions of the rDNA were determined in 24 taxones of Fagopyrum were cloned and sequenced;some related published sequences of genus Fagopyrum were analyzed in this paper.The result showed that the sequence of ITS ranged from 578 to 660 bp in length.The 5.8S subunit of Fagopyrum was found to consist of 163 or 164 bp nucleotides,while the length of ITS1 and ITS2 varied from 199 to 265bp and from 216 to 228 bp,respectively.The sequences of ITS(ITS1 and ITS2) were about 3～8 times more variable than those of the 5.8S subunit.The genetic distances varied from 0 to 0.128,with an average of 0.093.The genetic diversity between the cymosum group and the urophyllum group was larger,and within the urophyllum group was higher than that of within the cymosum group.The phylogenetic relationships were constructed using the maximum-parsimony and Bayesian analyses,and the two methods produced trees with largely congruent topology.Except for very few materials,the cymosum group and the urophyllum group formed two monophyletic branches,respectively.F.cymosum and F. tataricum were much more closely related than that of F.cymosum and F.esculentum. Although a 68 bp gap in ITS1 found in F.lineare,F.statice and F.leptopodum,yet a close relationship between F.lineare and F.urophyllum and a more farther relationship among F. lineare with F.statice and F.leptopodum.F.pleioramosum and F.capillatum were the sister species of F.gracilipes.Based on ITS analysis,it was showed that F.polychromofolium had close relationships with F.esculentum and F.esculentum ssp.ancestralis.3.The genetic diversity of the storage proteins of 76 cultivated buckwheat accessions (54 accessions of tartary buckwheat and 22 accessions of common buckwheat) was characterized by A-PAGE and SDS-PAGE,respectively.A total of 18 prolamin bands were detected by A-PAGE,among which 88.89%bands were polymorphic,indicating that some prolamin genetic variation was observed in cultivated buckwheat.15 albumn bands based on SDS-PAGE were observed in accessions.Most intense bands were in the range of molecular weights from 29 to 97.2 kDa.The average of genetic similarity coefficient based on prolamin bands was 0.784(in F.tataricum and F.esculentum were 0.892 and 0.681, respectively),while on prolamin and albumn bands was 0.742(in F.tataricum and F. esculentum were 0.864 and 0.633,respectively).Accessions of F.tataricum and F. esculentum showed significant interspecific variation in the A-PAGE and SDS-PAGE profile of the storage proteins.The cluster analysis indicated that all the accessions could be divided into 3 groups.The genetic variations among cultivated buckwheat accessions were associated with their geographic origins in some degree.4.Nine mainly agronomic traits and grain protein content of 76 cultivated buckwheat accessions(54 accessions of tartary buckwheat and 22 accessions of common buckwheat) collected from seven countries,were investigated based on analysis of variance,correlation, principal component and cluster.Higher variations of the nine agronomic traits were observed.It has shown that these materials had mid-low stalk,moderate number of main stem nodes,number of inflorescences and grain protein content,more number of primary branches,shorter total number of branches,lower 1000-seed yield and seed yield per plant. Multiple regression analysis showed that node number of branch,number of primary branches,total number of branches,number of inflorescences and 1000-seed yield were the main traits affected seed yield per plant in tartary buckwheat,while in common buckwheat were the plant height,number of inflorescences and period of duration.The direct effect of number of inflorescences was strongest both in tartary buckwheat and in common buckwheat.9 mainly agronomic characters were changed into 5 and 4 indexes through principal components analysis and the principal factors were found to contribute 87.77% and 92.09%to yield in tartary buckwheat and in common buckwheat,respectively.By clustering analysis,all tartary buckwheat accessions were divided into four groups,namely low-yield and late-maturing type,multi-branch and high-protein type,early-mature and high weight type,all common buckwheat accessions were clustered into two groups, namely early-mature-low stalk and high weight type and high-yield and high-protein content type.The genetic distances based on agronomic traits were not associated with their geographic distribution.According to these main characters,a batch of accessions with one or some elite agronomic performances were screened out.5.The contents of element such as Ca,Fe,Mg,Mn,Zn,Cr,Cu,Pb,Cd,As and Hg in the seeds of 59 accessions of cultivated buckwheat(38 accessions of tartary buckwheat,21 accessions of common buckwheat) were determined by the method of atomic absorption spectrometry(AAS) and atomic fluorescence spectrometry(AFS).Cluster analysis was made based on the inorganic element's contents.The results showed that cultivated buckwheat was rich in the contents of Ca,Mg,Cu and Cr,and the contents of Fe,Mn and Zn were quite high.The same element's average content of different materials had significant or extremely significant deviation.Except that the contents of Fe and Cr were higher than those of in common buckwheat,Pb's content was approximately consistent to that of in common buckwheat,other element's contents in tartary buckwheat were all lower than those of in common buckwheat.59 varieties were divided into 6 groups based on the element's content,and the variation of cluster analysis was not much associated with its geographical distribution.Nine accessions(i.e.PI 427235,PI 481653and PI 600909,etc.) which had higher contents of Fe,Zn and Cr were selected out.6.The diurnal variation trend of the total flavonoids contents in different organs on early flowering of buckwheat were studied,and provided the best collecting time and organs.The orthogonal experimental design was used to screen the extraction process of total flavonoids in buckwheat.The optimal extracting conditions were 75%ethanol as solvent,raw material and solvent ratio 1:25,extracting temperature 65℃,extracting time 2h.The diurnal variation of total flavonoids content in different organs of 4 materials was determined in the optimum extracting conditions.The results showed that the total flavonoids contents in different organs of the same species with various harvesting time were as follows:the contents in flowers were the highest,then the contents in leaves,stems and roots,respectively.And the contents in flowers and leaves were significantly higher than that in stems and roots.The diurnal changes of the total flavonoids contents from different organs in the different varieties were also quite different.It had the highest contents at 13:00 pm and 16:00 pm for total flavonoids of the flowers and leaves of buckwheat.The optimal harvesting time of medicinal common buckwheat and tartary buckwheat were at 13:00 pm to 19:00 pm and the best organs were the flowers and leaves.
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